This invention relates to a tire having an acrylic polymer film coating, which is protective, durable and aesthetically pleasing, and a method for making the same. In particular, the outer surface of the sidewall (non-tread) portion of the tire is coated with an acrylic polymer film.
It is known to treat the sidewalls of tires with silicon oil (polydimethylsiloxanes), to improve the appearance of the tire. For example, the silicon oil gives a glossy appearance, temporarily providing a “like-new” look to the tire. While silicon oils are relatively inexpensive to use, they can attract dust and dirt to the tire surface and can be slung onto the painted surfaces of an automobile. When the silicon oil fully dries, the tires tend to lose their glossy appearance. Further, silicon oil may degrade over time and weaken the tire sidewall, where the oil has been applied.
In addition to treatments designed to provide the like-new look to tires, it has been disclosed to apply certain decorative elements to the sidewall of a tire. Bryant et al, U.S. Pat. No. 4,684,420, provide paint compositions suitable for forming decals which can be applied to vehicle tire sidewalls. The compositions comprise a saturated elastomer having a glass transition temperature not higher than −40° C., a pigment in the range of 0.5 to 10 times the weight of elastomer, and a solvent.
In U.S. Pat. No. 6,030,676, Cottin et al. disclose another example of decorative pigments applied to the sidewalls of tires. In the following order, an adhesive layer, a pigment layer and a transparent layer are applied to the tire. The polymers used in the adhesive and transparent layers may be homopolymers and copolymers having as base at least one monomer selected form the group consisting of acrylic, methacrylic and vinyl esters. The polymers are applied in the form of an aqueous emulsion.
Despite earlier efforts, there remains a need for an improved coating for the sidewalls of tires, which meets most, if not all of the following objectives. The coating should be easy to apply in a single step and bonded directly to the outer surface of the tire, without the need for an intermediate adhesive layer. The coating should be provided in the form of a low-viscosity, aqueous solution, which may be sprayed on as a fine mist, at relatively high solids concentration. The coating should be water-resistant, once it has dried on the surface of the tire. The coating should dry quickly to form a transparent, non-tacky and glossy surface, which is resilient to tire flexing and torque, and resistant to heat, without cracking or flaking.